The type argument for HTMLCanvasElement toDataURL() api should not be nullable

Source/core/html/HTMLCanvasElement.idl

 /*
  * Copyright (C) 2006, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 31 matching lines @@
     //
     // Also note: the only reason this must return type "any" is to allow the
     // InspectorInstrumentation wrappers to be called for canvases. If that could be
     // handled differently the return type could be changed to "RenderingContext?"
     // and the [CallWith=ScriptState] extended attribute removed.
     //
     [CallWith=ScriptState] any getContext(DOMString contextId, [PermissiveDictionaryConversion] optional CanvasContextCreationAttributes attributes);
 
     // Note: The arguments argument is variadic in the spec, but not here as
     // only one extra argument is actually used.
-    // FIXME: type should not be nullable or have a default value.

[philipj_slow, 2015/07/23 08:02:12]

It still has a default value null, so leave that part of the FIXME. Actually
fixing that has the same problem as in
https://codereview.chromium.org/1225813003/ and I think you'll find this again
and again.

[shiva.jm, 2015/07/23 08:33:40]

Done.

-    [RaisesException] DOMString toDataURL(optional DOMString? type = null, optional any arguments);
+    [RaisesException] DOMString toDataURL(optional DOMString type = null, optional any arguments);
 };